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Gomes RP, Barbosa FF, Toledo MAS, Jorge SAC, Astray RM. Semliki Forest Virus (SFV) Self-Amplifying RNA Delivered to J774A.1 Macrophage Lineage by Its Association with a Purified Recombinant SFV Capsid Protein. Int J Mol Sci 2024; 25:7859. [PMID: 39063100 PMCID: PMC11276834 DOI: 10.3390/ijms25147859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 07/28/2024] Open
Abstract
The Semliki Forest virus capsid protein (C) is an RNA binding protein which exhibits both specific and unspecific affinities to single-strand nucleic acids. The putative use of the self-amplifying RNAs (saRNAs) of alphaviruses for biotechnological purpose is one of the main studied strategies concerning RNA-based therapies or immunization. In this work, a recombinant C protein from SFV was expressed and purified from bacteria and used to associate in vitro with a saRNA derived from SFV. Results showed that the purified form of C protein can associate with the saRNA even after high temperature treatment. The C protein was associated with a modified saRNA coding for the green fluorescent protein (GFP) and delivered to murine macrophage cells which expressed the GFP, showing that the saRNA was functional after being associated with the recombinant purified C protein.
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Affiliation(s)
- Roselane P. Gomes
- Viral Biotechnology Laboratory, Butantan Institute, Av. Vital Brasil 1500, São Paulo 05503-900, Brazil; (R.P.G.); (S.A.C.J.)
- Programa Interunidades em Biotecnologia, Universidade de São Paulo, São Paulo 05508-060, Brazil;
| | - Flavia F. Barbosa
- Programa Interunidades em Biotecnologia, Universidade de São Paulo, São Paulo 05508-060, Brazil;
- Multipurpose Laboratory, Butantan Institute, Av. Vital Brasil 1500, São Paulo 05503-900, Brazil
| | - Marcelo A. S. Toledo
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, RWTH Aachen University Medical School, 52074 Aachen, Germany;
- Center for Integrated Oncology Aachen Bonn Cologne Düsseldorf (CIO ABCD), 52074 Aachen, Germany
| | - Soraia A. C. Jorge
- Viral Biotechnology Laboratory, Butantan Institute, Av. Vital Brasil 1500, São Paulo 05503-900, Brazil; (R.P.G.); (S.A.C.J.)
| | - Renato M. Astray
- Multipurpose Laboratory, Butantan Institute, Av. Vital Brasil 1500, São Paulo 05503-900, Brazil
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2
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Sun Z, Wang M, Wang W, Li D, Wang J, Sui G. Getah virus capsid protein undergoes co-condensation with viral genomic RNA to facilitate virion assembly. Int J Biol Macromol 2024; 265:130847. [PMID: 38490381 DOI: 10.1016/j.ijbiomac.2024.130847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/10/2024] [Accepted: 03/11/2024] [Indexed: 03/17/2024]
Abstract
Getah virus (GETV) belongs to the Alphavirus genus in the Togaviridae family and is a zoonotic arbovirus causing disease in both humans and animals. The capsid protein (CP) of GETV regulates the viral core assembly, but the mechanism underlying this process is poorly understood. In this study, we demonstrate that CP undergoes liquid-liquid phase separation (LLPS) with the GETV genome RNA (gRNA) in vitro and forms cytoplasmic puncta in cells. Two regions of GETV gRNA (nucleotides 1-4000 and 5000-8000) enhance CP droplet formation in vitro and the lysine-rich Link region of CP is essential for its phase separation. CP(K/R) mutant with all lysines in the Link region replaced by arginines exhibits improved LLPS versus wild type (WT) CP, but CP(K/E) mutant with lysines substituted by glutamic acids virtually loses condensation ability. Consistently, recombinant virus mutant with CP(K/R) possesses significantly higher gRNA binding affinity, virion assembly efficiency and infectivity than the virus with WT-CP. Overall, our findings provide new insights into the understanding of GETV assembly and development of new antiviral drugs against alphaviruses.
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Affiliation(s)
- Zhenzhao Sun
- College of Life Science, Northeast Forestry University, Harbin 150040, People's Republic of China
| | - Ming Wang
- State Key Laboratory for Animal Disease Control and Prevention & National Data Center for Animal Infectious Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, People's Republic of China
| | - Wenmeng Wang
- College of Life Science, Northeast Forestry University, Harbin 150040, People's Republic of China
| | - Dangdang Li
- College of Life Science, Northeast Forestry University, Harbin 150040, People's Republic of China
| | - Jingfei Wang
- State Key Laboratory for Animal Disease Control and Prevention & National Data Center for Animal Infectious Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, People's Republic of China.
| | - Guangchao Sui
- College of Life Science, Northeast Forestry University, Harbin 150040, People's Republic of China.
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3
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Wang M, Wang L, Leng P, Guo J, Zhou H. Drugs targeting structural and nonstructural proteins of the chikungunya virus: A review. Int J Biol Macromol 2024; 262:129949. [PMID: 38311132 DOI: 10.1016/j.ijbiomac.2024.129949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 01/26/2024] [Accepted: 02/01/2024] [Indexed: 02/06/2024]
Abstract
Chikungunya virus (CHIKV) is a single positive-stranded RNA virus of the Togaviridae family and Alphavirus genus, with a typical lipid bilayer envelope structure, and is the causative agent of human chikungunya fever (CHIKF). The U.S. Food and Drug Administration has recently approved the first chikungunya vaccine, Ixchiq; however, vaccination rates are low, and CHIKF is prevalent owing to its periodic outbreaks. Thus, developing effective anti-CHIKV drugs in clinical settings is imperative. Viral proteins encoded by the CHIKV genome play vital roles in all stages of infection, and developing therapeutic agents that target these CHIKV proteins is an effective strategy to improve CHIKF treatment efficacy and reduce mortality rates. Therefore, in the present review article, we aimed to investigate the basic structure, function, and replication cycle of CHIKV and comprehensively outline the current status and future advancements in anti-CHIKV drug development, specifically targeting nonstructural (ns) proteins, including nsP1, nsP2, nsP3, and nsP4 and structural proteins such as capsid (C), E3, E2, 6K, and E1.
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Affiliation(s)
- Mengke Wang
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Lidong Wang
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Ping Leng
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Jinlin Guo
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Hao Zhou
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China; Chongqing Key Laboratory of Sichuan-Chongqing Co-construction for Diagnosis and Treatment of Infectious Diseases Integrated Traditional Chinese and Western Medicine, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400016, China.
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4
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Martin MF, Bonaventure B, McCray NE, Peersen OB, Rozen-Gagnon K, Stapleford KA. Distinct chikungunya virus polymerase palm subdomains contribute to virus replication and virion assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.15.575630. [PMID: 38293111 PMCID: PMC10827052 DOI: 10.1101/2024.01.15.575630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Alphaviruses encode an error-prone RNA-dependent RNA polymerase (RdRp), nsP4, required for genome synthesis, yet how the RdRp functions in the complete alphavirus life cycle is not well-defined. Previous work using chikungunya virus (CHIKV) has established the importance of the nsP4 residue cysteine 483 in maintaining viral genetic fidelity. Given the location of residue C483 in the nsP4 palm domain, we hypothesized that other residues within this domain and surrounding subdomains would also contribute to polymerase function. To test this hypothesis, we designed a panel of nsP4 variants via homology modeling based on the Coxsackievirus B3 3 polymerase. We rescued each variant in both mammalian and mosquito cells and discovered that the palm domain and ring finger subdomain contribute to polymerase host-specific replication and genetic stability. Surprisingly, in mosquito cells, these variants in the ring finger and palm domain were replication competent and produced viral structural proteins, but they were unable to produce infectious progeny, indicating a yet uncharacterized role for the polymerase in viral assembly. Finally, we have identified additional residues in the nsP4 palm domain that influence the genetic diversity of the viral progeny, potentially via an alteration in NTP binding and/or discrimination by the polymerase. Taken together, these studies highlight that distinct nsP4 subdomains regulate multiple processes of the alphavirus life cycle, placing nsP4 in a central role during the switch from RNA synthesis to packaging and assembly.
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Affiliation(s)
- Marie-France Martin
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Boris Bonaventure
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Nia E. McCray
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Olve B. Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | | | - Kenneth A. Stapleford
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
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Echavarria-Consuegra L, Dinesh Kumar N, van der Laan M, Mauthe M, Van de Pol D, Reggiori F, Smit JM. Mitochondrial protein BNIP3 regulates Chikungunya virus replication in the early stages of infection. PLoS Negl Trop Dis 2023; 17:e0010751. [PMID: 38011286 PMCID: PMC10703415 DOI: 10.1371/journal.pntd.0010751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 12/07/2023] [Accepted: 10/05/2023] [Indexed: 11/29/2023] Open
Abstract
Chikungunya virus (CHIKV) is a human pathogen causing outbreaks of febrile illness for which vaccines and specific treatments remain unavailable. Autophagy-related (ATG) proteins and autophagy receptors are a set of host factors that participate in autophagy, but have also shown to function in other unrelated cellular pathways. Although autophagy is reported to both inhibit and enhance CHIKV replication, the specific role of individual ATG proteins remains largely unknown. Here, a siRNA screen was performed to evaluate the importance of the ATG proteome and autophagy receptors in controlling CHIKV infection. We observed that 7 out of 50 ATG proteins impact the replication of CHIKV. Among those, depletion of the mitochondrial protein and autophagy receptor BCL2 Interacting Protein 3 (BNIP3) increased CHIKV infection. Interestingly, BNIP3 controls CHIKV independently of autophagy and cell death. Detailed analysis of the CHIKV viral cycle revealed that BNIP3 interferes with the early stages of infection. Moreover, the antiviral role of BNIP3 was found conserved across two distinct CHIKV genotypes and the closely related Semliki Forest virus. Altogether, this study describes a novel and previously unknown function of the mitochondrial protein BNIP3 in the control of the early stages of the alphavirus viral cycle.
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Affiliation(s)
- Liliana Echavarria-Consuegra
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Nilima Dinesh Kumar
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- Department of Biomedical Sciences of Cells & Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marleen van der Laan
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Mario Mauthe
- Department of Biomedical Sciences of Cells & Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Denise Van de Pol
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells & Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jolanda M. Smit
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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van der Meulen K, Smets G, Rüdelsheim P. Viral Replicon Systems and Their Biosafety Aspects. APPLIED BIOSAFETY 2023; 28:102-122. [PMID: 37342518 PMCID: PMC10278005 DOI: 10.1089/apb.2022.0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2023]
Abstract
Introduction Viral RNA replicons are self-amplifying RNA molecules generated by deleting genetic information of one or multiple structural proteins of wild-type viruses. Remaining viral RNA is used as such (naked replicon) or packaged into a viral replicon particle (VRP), whereby missing genes or proteins are supplied via production cells. Since replicons mostly originate from pathogenic wild-type viruses, careful risk consideration is crucial. Methods A literature review was performed compiling information on potential biosafety risks of replicons originating from positive- and negative-sense single-stranded RNA viruses (except retroviruses). Results For naked replicons, risk considerations included genome integration, persistence in host cells, generation of virus-like vesicles, and off-target effects. For VRP, the main risk consideration was formation of primary replication competent virus (RCV) as a result of recombination or complementation. To limit the risks, mostly measures aiming at reducing the likelihood of RCV formation have been described. Also, modifying viral proteins in such a way that they do not exhibit hazardous characteristics in the unlikely event of RCV formation has been reported. Discussion and Conclusion Despite multiple approaches developed to reduce the likelihood of RCV formation, scientific uncertainty remains on the actual contribution of the measures and on limitations to test their effectiveness. In contrast, even though effectiveness of each individual measure is unclear, using multiple measures on different aspects of the system may create a solid barrier. Risk considerations identified in the current study can also be used to support risk group assignment of replicon constructs based on a purely synthetic design.
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Williamson LE, Bandyopadhyay A, Bailey K, Sirohi D, Klose T, Julander JG, Kuhn RJ, Crowe JE. Structural constraints link differences in neutralization potency of human anti-Eastern equine encephalitis virus monoclonal antibodies. Proc Natl Acad Sci U S A 2023; 120:e2213690120. [PMID: 36961925 PMCID: PMC10068833 DOI: 10.1073/pnas.2213690120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 02/10/2023] [Indexed: 03/26/2023] Open
Abstract
Selection and development of monoclonal antibody (mAb) therapeutics against pathogenic viruses depends on certain functional characteristics. Neutralization potency, or the half-maximal inhibitory concentration (IC50) values, is an important characteristic of candidate therapeutic antibodies. Structural insights into the bases of neutralization potency differences between antiviral neutralizing mAbs are lacking. In this report, we present cryo-electron microscopy (EM) reconstructions of three anti-Eastern equine encephalitis virus (EEEV) neutralizing human mAbs targeting overlapping epitopes on the E2 protein, with greater than 20-fold differences in their respective IC50 values. From our structural and biophysical analyses, we identify several constraints that contribute to the observed differences in the neutralization potencies. Cryo-EM reconstructions of EEEV in complex with these Fab fragments reveal structural constraints that dictate intravirion or intervirion cross-linking of glycoprotein spikes by their IgG counterparts as a mechanism of neutralization. Additionally, we describe critical features for the recognition of EEEV by these mAbs including the epitope-paratope interaction surface, occupancy, and kinetic differences in on-rate for binding to the E2 protein. Each constraint contributes to the extent of EEEV inhibition for blockade of virus entry, fusion, and/or egress. These findings provide structural and biophysical insights into the differences in mechanism and neutralization potencies of these antibodies, which help inform rational design principles for candidate vaccines and therapeutic antibodies for all icosahedral viruses.
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Affiliation(s)
- Lauren E. Williamson
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN37232
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN37232
| | - Abhishek Bandyopadhyay
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - Kevin Bailey
- Institute for Antiviral Research, Utah State University, Logan, UT84335
| | - Devika Sirohi
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - Thomas Klose
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | | | - Richard J. Kuhn
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - James E. Crowe
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN37232
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN37232
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN37232
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8
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Self-assembly of dengue virus empty capsid-like particles in solution. iScience 2023; 26:106197. [PMID: 36890794 PMCID: PMC9986514 DOI: 10.1016/j.isci.2023.106197] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/11/2022] [Accepted: 02/08/2023] [Indexed: 02/17/2023] Open
Abstract
Nucleocapsid (NC) assembly is an essential step of the virus replication cycle. It ensures genome protection and transmission among hosts. Flaviviruses are human viruses for which envelope structure is well known, whereas no information on NC organization is available. Here we designed a dengue virus capsid protein (DENVC) mutant in which a highly positive spot conferred by arginine 85 in α4-helix was replaced by a cysteine residue, simultaneously removing the positive charge and restricting the intermolecular motion through the formation of a disulfide cross-link. We showed that the mutant self-assembles into capsid-like particles (CLP) in solution without nucleic acids. Using biophysical techniques, we investigated capsid assembly thermodynamics, showing that an efficient assembly is related to an increased DENVC stability due to α4/α4' motion restriction. To our knowledge, this is the first time that flaviviruses' empty capsid assembly is obtained in solution, revealing the R85C mutant as a powerful tool to understand the NC assembly mechanism.
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9
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Westcott CE, Isom CM, Karki D, Sokoloski KJ. Dancing with the Devil: A Review of the Importance of Host RNA-Binding Proteins to Alphaviral RNAs during Infection. Viruses 2023; 15:164. [PMID: 36680204 PMCID: PMC9865062 DOI: 10.3390/v15010164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/02/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023] Open
Abstract
Alphaviruses are arthropod-borne, single-stranded positive sense RNA viruses that rely on the engagement of host RNA-binding proteins to efficiently complete the viral lifecycle. Because of this reliance on host proteins, the identification of host/pathogen interactions and the subsequent characterization of their importance to viral infection has been an intensive area of study for several decades. Many of these host protein interaction studies have evaluated the Protein:Protein interactions of viral proteins during infection and a significant number of host proteins identified by these discovery efforts have been RNA Binding Proteins (RBPs). Considering this recognition, the field has shifted towards discovery efforts involving the direct identification of host factors that engage viral RNAs during infection using innovative discovery approaches. Collectively, these efforts have led to significant advancements in the understanding of alphaviral molecular biology; however, the precise extent and means by which many RBPs influence viral infection is unclear as their specific contributions to infection, as per any RNA:Protein interaction, have often been overlooked. The purpose of this review is to summarize the discovery of host/pathogen interactions during alphaviral infection with a specific emphasis on RBPs, to use new ontological analyses to reveal potential functional commonalities across alphaviral RBP interactants, and to identify host RBPs that have, and have yet to be, evaluated in their native context as RNA:Protein interactors.
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Affiliation(s)
- Claire E. Westcott
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Cierra M. Isom
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Deepa Karki
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Kevin J. Sokoloski
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, KY 40202, USA
- Center for Predictive Medicine for Biodefense and Emerging Infectious Disease (CPM), University of Louisville, Louisville, KY 40202, USA
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Skidmore AM, Bradfute SB. The life cycle of the alphaviruses: From an antiviral perspective. Antiviral Res 2023; 209:105476. [PMID: 36436722 PMCID: PMC9840710 DOI: 10.1016/j.antiviral.2022.105476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022]
Abstract
The alphaviruses are a widely distributed group of positive-sense, single stranded, RNA viruses. These viruses are largely arthropod-borne and can be found on all populated continents. These viruses cause significant human disease, and recently have begun to spread into new populations, such as the expansion of Chikungunya virus into southern Europe and the Caribbean, where it has established itself as endemic. The study of alphaviruses is an active and expanding field, due to their impacts on human health, their effects on agriculture, and the threat that some pose as potential agents of biological warfare and terrorism. In this systematic review we will summarize both historic knowledge in the field as well as recently published data that has potential to shift current theories in how alphaviruses are able to function. This review is comprehensive, covering all parts of the alphaviral life cycle as well as a brief overview of their pathology and the current state of research in regards to vaccines and therapeutics for alphaviral disease.
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Affiliation(s)
- Andrew M Skidmore
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, 915 Camino de Salud, IDTC Room 3245, Albuquerque, NM, 87131, USA.
| | - Steven B Bradfute
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, 915 Camino de Salud, IDTC Room 3330A, Albuquerque, NM, 87131, USA.
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Colunga-Saucedo M, Rubio-Hernandez EI, Coronado-Ipiña MA, Rosales-Mendoza S, Castillo CG, Comas-Garcia M. Construction of a Chikungunya Virus, Replicon, and Helper Plasmids for Transfection of Mammalian Cells. Viruses 2022; 15:132. [PMID: 36680173 PMCID: PMC9864538 DOI: 10.3390/v15010132] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/09/2022] [Accepted: 12/28/2022] [Indexed: 01/04/2023] Open
Abstract
The genome of Alphaviruses can be modified to produce self-replicating RNAs and virus-like particles, which are useful virological tools. In this work, we generated three plasmids for the transfection of mammalian cells: an infectious clone of Chikungunya virus (CHIKV), one that codes for the structural proteins (helper plasmid), and another one that codes nonstructural proteins (replicon plasmid). All of these plasmids contain a reporter gene (mKate2). The reporter gene in the replicon RNA and the infectious clone are synthesized from subgenomic RNA. Co-transfection with the helper and replicon plasmids has biotechnological/biomedical applications because they allow for the delivery of self-replicating RNA for the transient expression of one or more genes to the target cells.
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Affiliation(s)
- Mayra Colunga-Saucedo
- Sección de Genómica Médica, Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
| | - Edson I. Rubio-Hernandez
- Laboratorio de Células Troncales Humanas, Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
| | - Miguel A. Coronado-Ipiña
- Sección de Microscopía de Alta Resolución, Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
| | - Sergio Rosales-Mendoza
- Sección de Biotecnología, Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
- Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
| | - Claudia G. Castillo
- Laboratorio de Células Troncales Humanas, Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
| | - Mauricio Comas-Garcia
- Sección de Genómica Médica, Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
- Sección de Microscopía de Alta Resolución, Centro de Investigación en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, Mexico
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78295, Mexico
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12
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Adlhart M, Poetsch F, Hlevnjak M, Hoogmoed M, Polyansky A, Zagrovic B. Compositional complementarity between genomic RNA and coat proteins in positive-sense single-stranded RNA viruses. Nucleic Acids Res 2022; 50:4054-4067. [PMID: 35357492 PMCID: PMC9023274 DOI: 10.1093/nar/gkac202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/29/2022] [Indexed: 02/02/2023] Open
Abstract
During packaging in positive-sense single-stranded RNA (+ssRNA) viruses, coat proteins (CPs) interact directly with multiple regions in genomic RNA (gRNA), but the underlying physicochemical principles remain unclear. Here we analyze the high-resolution cryo-EM structure of bacteriophage MS2 and show that the gRNA/CP binding sites, including the known packaging signal, overlap significantly with regions where gRNA nucleobase-density profiles match the corresponding CP nucleobase-affinity profiles. Moreover, we show that the MS2 packaging signal corresponds to the global minimum in gRNA/CP interaction energy in the unstructured state as derived using a linearly additive model and knowledge-based nucleobase/amino-acid affinities. Motivated by this, we predict gRNA/CP interaction sites for a comprehensive set of 1082 +ssRNA viruses. We validate our predictions by comparing them with site-resolved information on gRNA/CP interactions derived in SELEX and CLIP experiments for 10 different viruses. Finally, we show that in experimentally studied systems CPs frequently interact with autologous coding regions in gRNA, in agreement with both predicted interaction energies and a recent proposal that proteins in general tend to interact with own mRNAs, if unstructured. Our results define a self-consistent framework for understanding packaging in +ssRNA viruses and implicate interactions between unstructured gRNA and CPs in the process.
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Affiliation(s)
- Marlene Adlhart
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Campus Vienna Biocenter 5, A-1030, Vienna, Austria
| | - Florian Poetsch
- Institute for Physiology and Pathophysiology, Center for Medical Research, Johannes Kepler University of Linz, Huemerstraße 3-5, 4020 Linz, Austria
| | - Mario Hlevnjak
- Division of Molecular Genetics, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Megan Hoogmoed
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Campus Vienna Biocenter 5, A-1030, Vienna, Austria
| | - Anton A Polyansky
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Campus Vienna Biocenter 5, A-1030, Vienna, Austria
| | - Bojan Zagrovic
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Campus Vienna Biocenter 5, A-1030, Vienna, Austria
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13
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Mebus-Antunes NC, Ferreira WS, Barbosa GM, Neves-Martins TC, Weissmuller G, Almeida FCL, Da Poian AT. The interaction of dengue virus capsid protein with negatively charged interfaces drives the in vitro assembly of nucleocapsid-like particles. PLoS One 2022; 17:e0264643. [PMID: 35231063 PMCID: PMC8887749 DOI: 10.1371/journal.pone.0264643] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 02/15/2022] [Indexed: 01/06/2023] Open
Abstract
Dengue virus (DENV) causes a major arthropod-borne viral disease, with 2.5 billion people living in risk areas. DENV consists in a 50 nm-diameter enveloped particle in which the surface proteins are arranged with icosahedral symmetry, while information about nucleocapsid (NC) structural organization is lacking. DENV NC is composed of the viral genome, a positive-sense single-stranded RNA, packaged by the capsid (C) protein. Here, we established the conditions for a reproducible in vitro assembly of DENV nucleocapsid-like particles (NCLPs) using recombinant DENVC. We analyzed NCLP formation in the absence or presence of oligonucleotides in solution using small angle X-ray scattering, Rayleigh light scattering as well as fluorescence anisotropy, and characterized particle structural properties using atomic force and transmission electron microscopy imaging. The experiments in solution comparing 2-, 5- and 25-mer oligonucleotides established that 2-mer is too small and 5-mer is sufficient for the formation of NCLPs. The assembly process was concentration-dependent and showed a saturation profile, with a stoichiometry of 1:1 (DENVC:oligonucleotide) molar ratio, suggesting an equilibrium involving DENVC dimer and an organized structure compatible with NCLPs. Imaging methods proved that the decrease in concentration to sub-nanomolar concentrations of DENVC allows the formation of regular spherical NCLPs after protein deposition on mica or carbon surfaces, in the presence as well as in the absence of oligonucleotides, in this latter case being surface driven. Altogether, the results suggest that in vitro assembly of DENV NCLPs depends on DENVC charge neutralization, which must be a very coordinated process to avoid unspecific aggregation. Our hypothesis is that a specific highly positive spot in DENVC α4-α4' is the main DENVC-RNA binding site, which is required to be firstly neutralized to allow NC formation.
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Affiliation(s)
- Nathane C. Mebus-Antunes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Wellington S. Ferreira
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Glauce M. Barbosa
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thais C. Neves-Martins
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gilberto Weissmuller
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabio C. L. Almeida
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- Centro Nacional de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Andrea T. Da Poian
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
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14
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Capsid-E2 Interactions Rescue Core Assembly in Viruses That Cannot Form Cytoplasmic Nucleocapsid Cores. J Virol 2021; 95:e0106221. [PMID: 34495691 DOI: 10.1128/jvi.01062-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alphavirus capsid proteins (CPs) have two domains: the N-terminal domain (NTD), which interacts with the viral RNA, and the C-terminal domain (CTD), which forms CP-CP interactions and interacts with the cytoplasmic domain of the E2 spike protein (cdE2). In this study, we examine how mutations in the CP NTD affect CP CTD interactions with cdE2. We changed the length and/or charge of the NTD of Ross River virus CP and found that changing the charge of the NTD has a greater impact on core and virion assembly than changing the length of the NTD. The NTD CP insertion mutants are unable to form cytoplasmic cores during infection, but they do form cores or core-like structures in virions. Our results are consistent with cdE2 having a role in core maturation during virion assembly and rescuing core formation when cytoplasmic cores are not assembled. We go on to find that the isolated cores from some mutant virions are now assembly competent in that they can be disassembled and reassembled back into cores. These results show how the two domains of CP may have distinct yet coordinated roles. IMPORTANCE Structural viral proteins have multiple roles during entry and assembly. The capsid protein (CP) of alphaviruses has one domain that interacts with the viral genome and another domain that interacts with the E2 spike protein. In this work, we determined that the length and/or charge of the CP affects cytoplasmic core formation. However, defects in cytoplasmic core formation can be overcome by E2-CP interactions, thus assembling a core or core-like complex in the virion. In the absence of both cytoplasmic cores and CP-E2 interactions, CP is not even packaged in the released virions, but some infectious particles are still released, presumably as RNA packaged in a glycoprotein-containing membrane shell. This suggests that the virus has multiple mechanisms in place to ensure the viral genome is surrounded by a capsid core during its life cycle.
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15
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Identification of Quinolinones as Antivirals against Venezuelan Equine Encephalitis Virus. Antimicrob Agents Chemother 2021; 65:e0024421. [PMID: 34152810 DOI: 10.1128/aac.00244-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Venezuelan equine encephalitis virus (VEEV) is a reemerging alphavirus that can cause encephalitis resulting in severe human morbidity and mortality. Using a high-throughput cell-based screen, we identified a quinolinone compound that protected against VEEV-induced cytopathic effects. Analysis of viral replication in cells identified several quinolinone compounds with potent inhibitory activity against vaccine and virulent strains of VEEV. These quinolinones also displayed inhibitory activity against additional alphaviruses, such as Mayaro virus and Ross River virus, although the potency was greatly reduced. Time-of-addition studies indicated that these compounds inhibit the early-to-mid stage of viral replication. Deep sequencing and reverse genetics studies identified two unique resistance mutations in the nsP2 gene (Y102S/C; stalk domain) that conferred VEEV resistance on this chemical series. Moreover, introduction of a K102Y mutation into the nsP2 gene enhanced the sensitivity of chikungunya virus (CHIKV) to this chemical series. Computational modeling of CHIKV and VEEV nsP2 identified a highly probable docking alignment for the quinolinone compounds that require a tyrosine residue at position 102 within the helicase stalk domain. These studies identified a class of compounds with antiviral activity against VEEV and other alphaviruses and provide further evidence that therapeutics targeting nsP2 may be useful against alphavirus infection.
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16
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Kiser LM, Sokoloski KJ, Hardy RW. Interactions between capsid and viral RNA regulate Chikungunya virus translation in a host-specific manner. Virology 2021; 560:34-42. [PMID: 34023723 PMCID: PMC8206026 DOI: 10.1016/j.virol.2021.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/19/2021] [Accepted: 04/28/2021] [Indexed: 12/24/2022]
Abstract
Alphaviruses are positive sense, RNA viruses commonly transmitted by an arthropod vector to a mammalian or avian host. In recent years, a number of the Alphavirus members have reemerged as public health concerns. Transmission from mosquito vector to vertebrate hosts requires an understanding of the interaction between the virus and both vertebrate and insect hosts to develop rational intervention strategies. The current study uncovers a novel role for capsid protein during Chikungunya virus replication whereby the interaction with viral RNA in the E1 coding region regulates protein synthesis processes early in infection. Studies done in both the mammalian and mosquito cells indicate that interactions between viral RNA and capsid protein have functional consequences that are host species specific. Our data support a vertebrate-specific role for capsid:vRNA interaction in temporally regulating viral translation in a manner dependent on the PI3K-AKT-mTOR pathway.
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Affiliation(s)
- Lauren M Kiser
- Department of Biology, College of Arts and Sciences, Indiana University, Bloomington, IN, USA
| | - Kevin J Sokoloski
- Department of Microbiology and Immunology and Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville School of Medicine, Louisville, KY, USA
| | - Richard W Hardy
- Department of Biology, College of Arts and Sciences, Indiana University, Bloomington, IN, USA.
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17
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Brown RS, Kim L, Kielian M. Specific Recognition of a Stem-Loop RNA Structure by the Alphavirus Capsid Protein. Viruses 2021; 13:v13081517. [PMID: 34452382 PMCID: PMC8402798 DOI: 10.3390/v13081517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 01/04/2023] Open
Abstract
Alphaviruses are small enveloped viruses with positive-sense RNA genomes. During infection, the alphavirus capsid protein (Cp) selectively packages and assembles with the viral genomic RNA to form the nucleocapsid core, a process critical to the production of infectious virus. Prior studies of the alphavirus Semliki Forest virus (SFV) showed that packaging and assembly are promoted by Cp binding to multiple high affinity sites on the genomic RNA. Here, we developed an in vitro Cp binding assay based on fluorescently labeled RNA oligos. We used this assay to explore the RNA sequence and structure requirements for Cp binding to site #1, the top binding site identified on the genomic RNA during all stages of virus assembly. Our results identify a stem-loop structure that promotes specific binding of the SFV Cp to site #1 RNA. This structure is also recognized by the Cps of the related alphaviruses chikungunya virus and Ross River virus.
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18
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Kumar R, Nehul S, Singh A, Tomar S. Identification and evaluation of antiviral potential of thymoquinone, a natural compound targeting Chikungunya virus capsid protein. Virology 2021; 561:36-46. [PMID: 34146962 DOI: 10.1016/j.virol.2021.05.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/20/2021] [Accepted: 05/30/2021] [Indexed: 10/21/2022]
Abstract
Capsid protein (CP) of Chikungunya virus (CHIKV) is a multifunctional protein with a conserved hydrophobic pocket that plays a crucial role in the capsid assembly and virus budding process. This study demonstrates antiviral activity of thymoquinone (TQ), a natural compound targeting the hydrophobic pocket of CP. The binding of TQ to the hydrophobic pocket of CHIKV CP was analysed by structure-based molecular docking, isothermal titration calorimetry and fluorescence spectroscopy. The binding constant KD obtained for TQ was 27 μM. Additionally, cell-based antiviral studies showed that TQ diminished CHIKV replication with an EC50 value 4.478 μM. Reduction in viral RNA copy number and viral replication as assessed by the qRT-PCR and immunofluorescence assay, confirmed the antiviral potential of TQ. Our study reveals that TQ is an effective antiviral targeting the hydrophobic pocket of CHIKV CP and may serve as the basis for development of a broad-spectrum therapy against alphaviral diseases.
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Affiliation(s)
- Ravi Kumar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Sanketkumar Nehul
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Ankur Singh
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Shailly Tomar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
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19
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Woodson M, Pajak J, Mahler BP, Zhao W, Zhang W, Arya G, White MA, Jardine PJ, Morais MC. A viral genome packaging motor transitions between cyclic and helical symmetry to translocate dsDNA. SCIENCE ADVANCES 2021; 7:7/19/eabc1955. [PMID: 33962953 PMCID: PMC8104870 DOI: 10.1126/sciadv.abc1955] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 03/19/2021] [Indexed: 06/12/2023]
Abstract
Molecular segregation and biopolymer manipulation require the action of molecular motors to do work by applying directional forces to macromolecules. The additional strand conserved E (ASCE) ring motors are an ancient family of molecular motors responsible for diverse biological polymer manipulation tasks. Viruses use ASCE segregation motors to package their genomes into their protein capsids and provide accessible experimental systems due to their relative simplicity. We show by cryo-EM-focused image reconstruction that ASCE ATPases in viral double-stranded DNA (dsDNA) packaging motors adopt helical symmetry complementary to their dsDNA substrates. Together with previous data, our results suggest that these motors cycle between helical and planar configurations, providing a possible mechanism for directional translocation of DNA. Similar changes in quaternary structure have been observed for proteasome and helicase motors, suggesting an ancient and common mechanism of force generation that has been adapted for specific tasks over the course of evolution.
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Affiliation(s)
- Michael Woodson
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Joshua Pajak
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
| | - Bryon P Mahler
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Wei Zhao
- Department of Diagnostic and Biological Sciences, School of Dentistry, and Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Wei Zhang
- Department of Diagnostic and Biological Sciences, School of Dentistry, and Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
- Characterization Facility, College of Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Gaurav Arya
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
| | - Mark A White
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Paul J Jardine
- Department of Diagnostic and Biological Sciences, School of Dentistry, and Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Marc C Morais
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA.
- Department of Diagnostic and Biological Sciences, School of Dentistry, and Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
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20
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Gaurav N, Tripathi PK, Kumar V, Chugh A, Sundd M, Patel AK. Role of nuclear localization signals in the DNA delivery function of Chikungunya virus capsid protein. Arch Biochem Biophys 2021; 702:108822. [PMID: 33722536 DOI: 10.1016/j.abb.2021.108822] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 02/14/2021] [Accepted: 02/22/2021] [Indexed: 11/24/2022]
Abstract
Capsids of several RNA viruses are reported to have unconventional roles attributed to their subcellular trafficking property. The capsid of CHIKV is also found to localize in the nucleus, but the rationale is not yet clear. To understand the role of the nuclear-localized capsid, we examined the nucleic acid binding and cargo delivery activity of the CHIKV capsid. We used bacterially purified capsid protein to probe the binding affinity with CHIKV genome-specific and non-specific nucleic acids. We found that the capsid was able to bind non-specifically to different forms of nucleic acids. The successful transfection of GFP-tagged plasmid DNA by CHIKV capsid protein shows the DNA delivery ability of the protein. Further, we selected and investigated the DNA binding and cargo delivery activity of commercially synthesized Nuclear Localization Signal sequences (NLS 1 and NLS2) of capsid protein. Both peptides showed comparable DNA binding affinity, however, only the NLS1 peptide was capable of delivering plasmid DNA inside the cell. Furthermore, the cellular uptake study using the FITC-labelled NLS1 peptide was performed to highlight the membrane penetrating ability. Structural analysis was performed using circular dichroism and NMR spectroscopy to elucidate the transfection ability of the NLS1 peptides. Our findings suggest that the capsid of CHIKV might influence cellular trafficking in the infected cell via non-specific interactions. Our study also indicates the significance of NLS sequences in the multifunctionality of CHIKV capsid protein.
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Affiliation(s)
- Nitika Gaurav
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Praveen Kumar Tripathi
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Vivek Kumar
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Archana Chugh
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Monica Sundd
- National Institute of Immunology, Aruna Asaf Ali Marg, JNU Campus, New Delhi, 110067, India
| | - Ashok Kumar Patel
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, 110016, India.
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21
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The Alphaviral Capsid Protein Inhibits IRAK1-Dependent TLR Signaling. Viruses 2021; 13:v13030377. [PMID: 33673546 PMCID: PMC7997285 DOI: 10.3390/v13030377] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/24/2021] [Accepted: 02/26/2021] [Indexed: 12/20/2022] Open
Abstract
Alphaviruses are arthropod-borne RNA viruses which can cause either mild to severe febrile arthritis which may persist for months, or encephalitis which can lead to death or lifelong cognitive impairments. The non-assembly molecular role(s), functions, and protein–protein interactions of the alphavirus capsid proteins have been largely overlooked. Here we detail the use of a BioID2 biotin ligase system to identify the protein–protein interactions of the Sindbis virus capsid protein. These efforts led to the discovery of a series of novel host–pathogen interactions, including the identification of an interaction between the alphaviral capsid protein and the host IRAK1 protein. Importantly, this capsid–IRAK1 interaction is conserved across multiple alphavirus species, including arthritogenic alphaviruses SINV, Ross River virus, and Chikungunya virus; and encephalitic alphaviruses Eastern Equine Encephalitis virus, and Venezuelan Equine Encephalitis virus. The impact of the capsid–IRAK1 interaction was evaluated using a robust set of cellular model systems, leading to the realization that the alphaviral capsid protein specifically inhibits IRAK1-dependent signaling. This inhibition represents a means by which alphaviruses may evade innate immune detection and activation prior to viral gene expression. Altogether, these data identify novel capsid protein–protein interactions, establish the capsid–IRAK1 interaction as a common alphavirus host–pathogen interface, and delineate the molecular consequences of the capsid–IRAK1 interaction on IRAK1-dependent signaling.
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22
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Nowee G, Bakker JW, Geertsema C, Ros VID, Göertz GP, Fros JJ, Pijlman GP. A Tale of 20 Alphaviruses; Inter-species Diversity and Conserved Interactions Between Viral Non-structural Protein 3 and Stress Granule Proteins. Front Cell Dev Biol 2021; 9:625711. [PMID: 33644063 PMCID: PMC7905232 DOI: 10.3389/fcell.2021.625711] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 01/12/2021] [Indexed: 12/14/2022] Open
Abstract
Alphaviruses infect a diverse range of host organisms including mosquitoes, mammals, and birds. The enigmatic alphavirus non-structural protein 3 (nsP3) has an intrinsically disordered, C-terminal hypervariable domain (HVD) that can interact with a variety of host proteins associated with stress granules (SGs). The HVD displays the highest variability across the more than 30 known alphaviruses, yet it also contains several motifs that are conserved amongst different subgroups of alphaviruses. For some alphaviruses, specific nsP3–SG protein interactions are essential for virus replication. However, it remains difficult to attribute general roles to these virus-host interactions, as multiple amino acid motifs in the HDV display a degree of redundancy and previous studies were performed with a limited number of alphaviruses. To better understand nsP3-host protein interactions we conducted comprehensive co-localization experiments with the nsP3s of 20 diverse alphaviruses: chikungunya, Semliki Forest, Sindbis, Bebaru, Barmah Forest, Getah, Mayaro, Middelburg, O'nyong-nyong, Ross River QML and T48, Una, Whataroa, Southern Elephant Seal, Eilat, Tai Forest (TAFV), Venezuelan/Eastern/Western equine encephalitis (V/E/WEEV) and the aquatic Salmonid alphavirus (SAV), with three different SG proteins (G3BP and its insect homolog Rasputin, FMRP) and BIN1 in mammalian and mosquito cell lines. Despite that all terrestrial alphavirus nsP3s contained at least one BIN1-binding motif (PxPxPR), not all nsP3s co-localized with BIN1. Further, all alphaviruses except SAV, TAFV and VEEV displayed co-localization with G3BP. Although viruses lacking FGxF-like motifs contained Agenet-like domain binding motifs to facilitate interaction with FMRP, cytoplasmic nsP3 granules of all tested alphaviruses co-localized with FMRP. Crispr-Cas9 knockout of G3BP in mammalian cells abolished nsP3-FMRP co-localization for all alphaviruses except V/E/WEEV nsP3s that bind FMRP directly. G3BP knockout also changed nsP3 subcellular localization of Bebaru, Barmah Forest, Getah, and Sindbis viruses. Taken together this study paints a more detailed picture of the diverse interactions between alphavirus nsP3 and SG-associated host proteins. The interaction between nsP3 and G3BP clearly plays a central role and results in recruitment of additional host proteins such as FMRP. However, direct binding of FMRP can make the interaction with G3BP redundant which exemplifies the alternate evolutionary paths of alphavirus subgroups.
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Affiliation(s)
- Gwen Nowee
- Laboratory of Virology, Wageningen University, Wageningen, Netherlands
| | - Julian W Bakker
- Laboratory of Virology, Wageningen University, Wageningen, Netherlands
| | - Corinne Geertsema
- Laboratory of Virology, Wageningen University, Wageningen, Netherlands
| | - Vera I D Ros
- Laboratory of Virology, Wageningen University, Wageningen, Netherlands
| | - Giel P Göertz
- Laboratory of Virology, Wageningen University, Wageningen, Netherlands
| | - Jelke J Fros
- Laboratory of Virology, Wageningen University, Wageningen, Netherlands
| | - Gorben P Pijlman
- Laboratory of Virology, Wageningen University, Wageningen, Netherlands
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23
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Visualization of the Oncolytic Alphavirus M1 Life Cycle in Cancer Cells. Virol Sin 2021; 36:655-666. [PMID: 33481190 DOI: 10.1007/s12250-020-00339-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 10/26/2020] [Indexed: 01/16/2023] Open
Abstract
Oncolytic alphavirus M1 has been shown to selectively target and kill cancer cells, but cytopathic morphologies induced by M1 virus and the life cycle of the M1 strain in cancer cells remain unclear. Here, we study the key stages of M1 virus infection and replication in the M1 virus-sensitive HepG2 liver cancer cell line by transmission electron microscopy, specifically examining viral entry, assembly, maturation and release. We found that M1 virus induces vacuolization of cancer cells during infection and ultimately nuclear marginalization, a typical indicator of apoptosis. Specifically, our results suggest that the endoplasmic reticulum participates in the assembly of nucleocapsids. In the early and late stage of infection, three kinds of special cytopathic vacuoles are formed and appear to be involved in the replication, maturation and release of the virus. Taken together, our data displayed the process of M1 virus infection of tumor cells and provide the structural basis for the study of M1 virus-host interactions.
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24
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Thite A, Agrawal M, Pavitrakar D, Cherian S, Damle R. Delineation of an epitope recognized by a chikungunya virus anti-capsid monoclonal antibody on the protease domain using an immuno-informatics approach. J Biomol Struct Dyn 2021; 40:5623-5633. [PMID: 33480314 DOI: 10.1080/07391102.2021.1872416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The capsid-protein (CP) of chikungunya virus (CHIKV) is reported to generate a primary immune response in infected individuals during disease progression. CP-specific monoclonal antibodies (mAbs) developed in our laboratory, exhibited promising potential in diagnosing recent CHIKV infection in IgM capture ELISA. In this study we focused on the molecular and structural characterization of one such representative mAb ClVE4/D9 to delineate the epitope recognized by it using an immuno-informatics approach. The antigen-antibody interacting residues were found to lie within the dimer interface region of the CP, also predicted as a conformational epitope. This implies that the mAb could interfere during the process of nucleocapsid assembly, ultimately preventing budding and egress of the virus particle. The binding specificity of the mAb highlights the possibility of using this anti-CP antibody for therapeutic or prophylactic treatment against CHIKV.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Aabha Thite
- NIBEC, Interactive Research School for Health Affairs (IRSHA), Bharati Vidyapeeth (Deemed to be University), Dhankawadi, Pune, Maharashtra, India.,Department of Bioinformatics & Data Management, National Institute of Virology, Pune, India
| | - Megha Agrawal
- Department of Bioinformatics & Data Management, National Institute of Virology, Pune, India
| | - Daya Pavitrakar
- NIBEC, Interactive Research School for Health Affairs (IRSHA), Bharati Vidyapeeth (Deemed to be University), Dhankawadi, Pune, Maharashtra, India
| | - Sarah Cherian
- Department of Bioinformatics & Data Management, National Institute of Virology, Pune, India
| | - Rekha Damle
- NIBEC, Interactive Research School for Health Affairs (IRSHA), Bharati Vidyapeeth (Deemed to be University), Dhankawadi, Pune, Maharashtra, India
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25
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Brown RS, Anastasakis DG, Hafner M, Kielian M. Multiple capsid protein binding sites mediate selective packaging of the alphavirus genomic RNA. Nat Commun 2020; 11:4693. [PMID: 32943634 PMCID: PMC7499256 DOI: 10.1038/s41467-020-18447-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 08/24/2020] [Indexed: 12/16/2022] Open
Abstract
The alphavirus capsid protein (Cp) selectively packages genomic RNA (gRNA) into the viral nucleocapsid to produce infectious virus. Using photoactivatable ribonucleoside crosslinking and an innovative biotinylated Cp retrieval method, here we comprehensively define binding sites for Semliki Forest virus (SFV) Cp on the gRNA. While data in infected cells demonstrate Cp binding to the proposed genome packaging signal (PS), mutagenesis experiments show that PS is not required for production of infectious SFV or Chikungunya virus. Instead, we identify multiple Cp binding sites that are enriched on gRNA-specific regions and promote infectious SFV production and gRNA packaging. Comparisons of binding sites in cytoplasmic vs. viral nucleocapsids demonstrate that budding causes discrete changes in Cp-gRNA interactions. Notably, Cp’s top binding site is maintained throughout virus assembly, and specifically binds and assembles with Cp into core-like particles in vitro. Together our data suggest a model for selective alphavirus genome recognition and assembly. Alphaviruses need to selectively package genomic viral RNA for transmission, but the packaging mechanism remains unclear. Here, Brown et al. combine PAR-CLIP with biotinylated capsid protein (Cp) retrieval and identify multiple Cp binding sites on genomic viral RNA that promote virion formation.
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Affiliation(s)
- Rebecca S Brown
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Dimitrios G Anastasakis
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Disease, Bethesda, MD, 20892, USA
| | - Markus Hafner
- Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Disease, Bethesda, MD, 20892, USA
| | - Margaret Kielian
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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Removing the Polyanionic Cargo Requirement for Assembly of Alphavirus Core-Like Particles to Make an Empty Alphavirus Core. Viruses 2020; 12:v12080846. [PMID: 32756493 PMCID: PMC7472333 DOI: 10.3390/v12080846] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 12/18/2022] Open
Abstract
The assembly of alphavirus nucleocapsid cores requires electrostatic interactions between the positively charged N-terminus of the capsid protein (CP) and the encapsidated polyanionic cargo. This system differs from many other viruses that can self-assemble particles in the absence of cargo, or form “empty” particles. We hypothesized that the introduction of a mutant, anionic CP could replace the need for charged cargo during assembly. In this work, we produced a CP mutant, Minus 38 (M38), where all N-terminal charged residues are negatively-charged. When wild-type (WT) and M38 CPs were mixed, they assembled into core-like particles (CLPs). These “empty” particles were of similar size and morphology to WT CLPs assembled with DNA cargo, but did not contain nucleic acid. When DNA cargo was added to the assembly mixture, the amount of M38 CP that was assembled into CLPs decreased, but was not fully excluded from the CLPs, suggesting that M38 competes with DNA to interact with WT CPs. The composition of CLPs can be tuned by altering the order of addition of M38 CP, WT CP, and DNA cargo. The ability to produce alphavirus CLPs that contain a range of amounts of encapsidated cargo, including none, introduces a new platform for packaging cargo for delivery or imaging purposes.
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Button JM, Qazi SA, Wang JCY, Mukhopadhyay S. Revisiting an old friend: new findings in alphavirus structure and assembly. Curr Opin Virol 2020; 45:25-33. [PMID: 32683295 DOI: 10.1016/j.coviro.2020.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 06/04/2020] [Accepted: 06/16/2020] [Indexed: 01/17/2023]
Abstract
Alphaviruses are transmitted by an arthropod vector to a vertebrate host. The disease pathologies, cellular environments, immune responses, and host factors are very different in these organisms. Yet, the virus is able to infect, replicate, and assemble into new particles in these two animals using one set of genetic instructions. The balance between conserved mechanisms and unique strategies during virus assembly is critical for fitness of the virus. In this review, we discuss new findings in receptor binding, polyprotein topology, nucleocapsid core formation, and particle budding that have emerged in the last five years and share opinions on how these new findings might answer some questions regarding alphavirus structure and assembly.
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Affiliation(s)
- Julie M Button
- Department of Molecular and Cellular Biochemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405, United States
| | - Shefah A Qazi
- Department of Biology, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405, United States
| | - Joseph Che-Yen Wang
- Department of Microbiology and Immunology, Penn State College of Medicine, 700 HMC Crescent Road, Hershey, PA 17033, United States
| | - Suchetana Mukhopadhyay
- Department of Biology, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405, United States.
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28
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Abstract
Alphaviruses are enveloped positive-sense RNA viruses that can cause serious human illnesses such as polyarthritis and encephalitis. Despite their widespread distribution and medical importance, there are no licensed vaccines or antivirals to combat alphavirus infections. Berberine chloride (BBC) is a pan-alphavirus inhibitor that was previously identified in a replicon-based small-molecule screen. This work showed that BBC inhibits alphavirus replication but also suggested that BBC might have additional effects later in the viral life cycle. Here, we show that BBC has late effects that target the virus nucleocapsid (NC) core. Infected cells treated with BBC late in infection were unable to form stable cytoplasmic NCs or assembly intermediates, as assayed by gradient sedimentation. In vitro studies with recombinant capsid protein (Cp) and purified genomic RNA (gRNA) showed that BBC perturbs core-like particle formation and potentially traps the assembly process in intermediate states. Particles produced from BBC-treated cells were less infectious, despite efficient particle production and only minor decreases in genome packaging. In addition, BBC treatment of free virus particles strongly decreased alphavirus infectivity. In contrast, the infectivity of the negative-sense RNA virus vesicular stomatitis virus was resistant to BBC treatment of infected cells or free virus. Together, our data indicate that BBC alters alphavirus Cp-gRNA interactions and oligomerization and suggest that this may cause defects in NC assembly and in disassembly during subsequent virus entry. Thus, BBC may be considered a novel alphavirus NC assembly inhibitor.IMPORTANCE The alphavirus chikungunya virus (CHIKV) is an example of an emerging human pathogen with increased and rapid global spread. Although an acute CHIKV infection is rarely fatal, many patients suffer from debilitating chronic arthralgia for years. Antivirals against chikungunya and other alphaviruses have been identified in vitro, but to date none have been shown to be efficacious and have been licensed for human use. Here, we investigated a small molecule, berberine chloride (BBC), and showed that it inhibited infectious virus production by several alphaviruses including CHIKV. BBC acted on a late step in the alphavirus exit pathway, namely the formation of the nucleocapsid containing the infectious viral RNA. Better understanding of nucleocapsid formation and its inhibition by BBC will provide important information on the mechanisms of infectious alphavirus production and may enable their future targeting in antiviral strategies.
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Alphavirus Replication: The Role of Cardiac Glycosides and Ion Concentration in Host Cells. BIOMED RESEARCH INTERNATIONAL 2020; 2020:2813253. [PMID: 32461975 PMCID: PMC7232666 DOI: 10.1155/2020/2813253] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/31/2020] [Accepted: 04/15/2020] [Indexed: 01/07/2023]
Abstract
Alphaviruses are arthropod-borne viruses that can cause fever, rash, arthralgias, and encephalitis. The mosquito species Aedes aegypti and Aedes albopictus are the most frequent transmitters of alphaviruses. There are no effective vaccines or specific antivirals available for the treatment of alphavirus-related infections. Interestingly, changes in ion concentration in host cells have been characterized as critical regulators of the alphavirus life cycle, including fusion with the host cell, glycoprotein trafficking, genome translation, and viral budding. Cardiac glycosides, which are classical inhibitors of the Na+ K+ ATPase (NKA), can inhibit alphavirus replication although their mechanisms of action are poorly understood. Nonetheless, results from multiple studies suggest that inhibition of NKA may be a suitable strategy for the development of alphavirus-specific antiviral treatments. This review is aimed at exploring the role of changes in ion concentration during alphavirus replication and at considering the possibility of NKA as a potential therapeutic target for antiviral drugs.
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Echavarria-Consuegra L, Smit JM, Reggiori F. Role of autophagy during the replication and pathogenesis of common mosquito-borne flavi- and alphaviruses. Open Biol 2020; 9:190009. [PMID: 30862253 PMCID: PMC6451359 DOI: 10.1098/rsob.190009] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Arboviruses that are transmitted to humans by mosquitoes represent one of the most important causes of febrile illness worldwide. In recent decades, we have witnessed a dramatic re-emergence of several mosquito-borne arboviruses, including dengue virus (DENV), West Nile virus (WNV), chikungunya virus (CHIKV) and Zika virus (ZIKV). DENV is currently the most common mosquito-borne arbovirus, with an estimated 390 million infections worldwide annually. Despite a global effort, no specific therapeutic strategies are available to combat the diseases caused by these viruses. Multiple cellular pathways modulate the outcome of infection by either promoting or hampering viral replication and/or pathogenesis, and autophagy appears to be one of them. Autophagy is a degradative pathway generally induced to counteract viral infection. Viruses, however, have evolved strategies to subvert this pathway and to hijack autophagy components for their own benefit. In this review, we will focus on the role of autophagy in mosquito-borne arboviruses with emphasis on DENV, CHIKV, WNV and ZIKV, due to their epidemiological importance and high disease burden.
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Affiliation(s)
- Liliana Echavarria-Consuegra
- 1 Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen , Groningen , The Netherlands
| | - Jolanda M Smit
- 1 Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen , Groningen , The Netherlands
| | - Fulvio Reggiori
- 2 Department of Cell Biology, University of Groningen, University Medical Center Groningen , Groningen , The Netherlands
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31
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Abstract
RNA viruses carry out selective packaging of their genomes in a variety of ways, many involving a genomic packaging signal. The first coronavirus packaging signal was discovered nearly thirty years ago, but how it functions remains incompletely understood. This review addresses the current state of knowledge of coronavirus genome packaging, which has mainly been studied in two prototype species, mouse hepatitis virus and transmissible gastroenteritis virus. Despite the progress that has been made in the mapping and characterization of some packaging signals, there is conflicting evidence as to whether the viral nucleocapsid protein or the membrane protein plays the primary role in packaging signal recognition. The different models for the mechanism of genomic RNA packaging that have been prompted by these competing views are described. Also discussed is the recent exciting discovery that selective coronavirus genome packaging is critical for in vivo evasion of the host innate immune response. Selective incorporation of the coronavirus genome into virions is mediated by a cis-acting RNA packaging signal. Packaging signals vary across different coronavirus genera and lineages. Different lines of evidence attribute packaging signal recognition to either the nucleocapsid or the membrane protein. Selective coronavirus genome packaging plays a role in evasion of host innate immunity.
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Affiliation(s)
- Paul S Masters
- Wadsworth Center, New York State Department of Health, Albany, NY, 12201, United States.
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32
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Comas-Garcia M. Packaging of Genomic RNA in Positive-Sense Single-Stranded RNA Viruses: A Complex Story. Viruses 2019; 11:v11030253. [PMID: 30871184 PMCID: PMC6466141 DOI: 10.3390/v11030253] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 02/06/2023] Open
Abstract
The packaging of genomic RNA in positive-sense single-stranded RNA viruses is a key part of the viral infectious cycle, yet this step is not fully understood. Unlike double-stranded DNA and RNA viruses, this process is coupled with nucleocapsid assembly. The specificity of RNA packaging depends on multiple factors: (i) one or more packaging signals, (ii) RNA replication, (iii) translation, (iv) viral factories, and (v) the physical properties of the RNA. The relative contribution of each of these factors to packaging specificity is different for every virus. In vitro and in vivo data show that there are different packaging mechanisms that control selective packaging of the genomic RNA during nucleocapsid assembly. The goals of this article are to explain some of the key experiments that support the contribution of these factors to packaging selectivity and to draw a general scenario that could help us move towards a better understanding of this step of the viral infectious cycle.
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Affiliation(s)
- Mauricio Comas-Garcia
- Research Center for Health Sciences and Biomedicine (CICSaB), Universidad Autónoma de San Luis Potosí (UASLP), Av. Sierra Leona 550 Lomas 2da Seccion, 72810 San Luis Potosi, Mexico.
- Department of Sciences, Universidad Autónoma de San Luis Potosí (UASLP), Av. Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosi, Mexico.
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The Alphavirus E2 Membrane-Proximal Domain Impacts Capsid Interaction and Glycoprotein Lattice Formation. J Virol 2019; 93:JVI.01881-18. [PMID: 30463969 DOI: 10.1128/jvi.01881-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 11/13/2018] [Indexed: 11/20/2022] Open
Abstract
Alphaviruses are small enveloped RNA viruses that bud from the host cell plasma membrane. Alphavirus particles have a highly organized structure, with a nucleocapsid core containing the RNA genome surrounded by the capsid protein, and a viral envelope containing 80 spikes, each a trimer of heterodimers of the E1 and E2 glycoproteins. The capsid protein and envelope proteins are both arranged in organized lattices that are linked via the interaction of the E2 cytoplasmic tail/endodomain with the capsid protein. We previously characterized the role of two highly conserved histidine residues, H348 and H352, located in an external, juxtamembrane region of the E2 protein termed the D-loop. Alanine substitutions of H348 and H352 inhibit virus growth by impairing late steps in the assembly/budding of virus particles at the plasma membrane. To investigate this budding defect, we selected for revertants of the E2-H348/352A double mutant. We identified eleven second-site revertants with improved virus growth and mutations in the capsid, E2 and E1 proteins. Multiple isolates contained the mutation E2-T402K in the E2 endodomain or E1-T317I in the E1 ectodomain. Both of these mutations were shown to partially restore H348/352A growth and virus assembly/budding, while neither rescued the decreased thermostability of H348/352A. Within the alphavirus particle, these mutations are positioned to affect the E2-capsid interaction or the E1-mediated intertrimer interactions at the 5-fold axis of symmetry. Together, our results support a model in which the E2 D-loop promotes the formation of the glycoprotein lattice and its interactions with the internal capsid protein lattice.IMPORTANCE Alphaviruses include important human pathogens such as Chikungunya and the encephalitic alphaviruses. There are currently no licensed alphavirus vaccines or effective antiviral therapies, and more molecular information on virus particle structure and function is needed. Here, we highlight the important role of the E2 juxtamembrane D-loop in mediating virus budding and particle production. Our results demonstrated that this E2 region affects both the formation of the external glycoprotein lattice and its interactions with the internal capsid protein shell.
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34
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Twarock R, Bingham RJ, Dykeman EC, Stockley PG. A modelling paradigm for RNA virus assembly. Curr Opin Virol 2018; 31:74-81. [PMID: 30078702 PMCID: PMC6281560 DOI: 10.1016/j.coviro.2018.07.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 07/04/2018] [Indexed: 12/14/2022]
Abstract
Virus assembly, a key stage in any viral life cycle, had long been considered to be primarily driven by protein-protein interactions and nonspecific interactions between genomic RNA and capsid protein. We review here a modelling paradigm for RNA virus assembly that illustrates the crucial roles of multiple dispersed, specific interactions between viral genomes and coat proteins in capsid assembly. The model reveals how multiple sequence-structure motifs in the genomic RNA, termed packaging signals, with a shared coat protein recognition motif enable viruses to overcome a viral assembly-equivalent of Levinthal's Paradox in protein folding. The fitness advantages conferred by this mechanism suggest that it should be widespread in viruses, opening up new perspectives on viral evolution and anti-viral therapy.
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Affiliation(s)
- Reidun Twarock
- York Centre for Cross-disciplinary Systems Analysis, University of York, York YO10 5GE, UK; Department of Mathematics, University of York, York YO10 5DD, UK; Department of Biology, University of York, York YO10 5NG, UK.
| | - Richard J Bingham
- York Centre for Cross-disciplinary Systems Analysis, University of York, York YO10 5GE, UK; Department of Mathematics, University of York, York YO10 5DD, UK; Department of Biology, University of York, York YO10 5NG, UK
| | - Eric C Dykeman
- York Centre for Cross-disciplinary Systems Analysis, University of York, York YO10 5GE, UK; Department of Mathematics, University of York, York YO10 5DD, UK
| | - Peter G Stockley
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT UK
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